中文摘要：

当路桥过渡段不设桥头搭板时,在引道和桥台之间由于工后沉降差所造成的台阶是桥头跳车的主要诱因,不同的台阶高度会对行车安全造成不同的影响。但目前对于容许台阶高度尚未形成一致的认识。文中通过对未设搭板情况下桥头跳车形成机理的分析,建立路桥过渡段台阶高度与减速度之间的关系,进而以减速度为依据分析台阶高度对交通安全的影响,分别确定了行车速度为80km/h、100km/h、120km/h时3种情况下,不同影响等级所对应的容许台阶高度。研究表明：从交通流运行特征的角度分析台阶高度与交通安全的关系是可行的,未设搭板情况下容许台阶高度与车速紧密相关,其取值随着行车速度的增加不断减小。

英文摘要：

The differential settlement between the bridge and the embankment always results in bumping at Bridge-Head （VBBH） when there is no approach slab for transition section between bridge abutment and embankment. However, there is no unanimous consensus on allowable differential settlement between the bridge and the embankment. This paper is to quantitatively study the relationship model between bridgehead differential settlement and deceleration. Impact of VBBH on traffic safety is divided into three levels based on deceleration. The allowable differential settlement between bridge and approach embankment corresponding different impact level are determined when the speed is 80 km/h, 100 km/h and 120 km/h. The research shows that without approach slab the allowable step height is closely related with the driving speed and the value is decreasing while the driving speed is increasing.